The smog over Los Angeles, the grey, chemical haze in Beijing and brown over Mexico City are the world’s collective images of air pollution. And while no doubt such pollution is dangerous, the images miss a key point -- some of the most dangerous air pollution is found indoors rather than outdoors. Because of imagery, our allocation of effort and resources addresses one side of a problem but not another.
Fifty years ago, if you were to walk into a home and see a vacuum cleaner, you would have been taken aback by encountering the device. If you were to walk into a home today and not come across at least one vacuum cleaner, you would be taken aback.